A receiver for a wireless communication device comprising a mechanism for performing spur mitigation. An AGC unit of the receiver is operable to determine when an amplitude of an ADC output signal associated with a received RF signal is outside a predetermined amplitude range. The AGC unit is operable to modify a gain associated with a VGA such that the ADC output signal has an amplitude within the predetermined amplitude rage. The first spur mitigation unit is operable to determine an estimate of a spur signal of the ADC output signal and remove the spur signal from the ADC output signal based on the estimate of the spur signal. The first spur mitigation unit comprises a moving average filter operable to generate the estimate of the spur signal. The AGC unit is further operable to reset the moving average filter of the first spur mitigation unit when the AGC unit modifies the gain associated with the VGA.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A receiver for a wireless communication device, the receiver comprising: a variable gain amplifier (VGA) operable to change an amplitude of an RF signal received at the receiver; an analog-to-digital converter (ADC) coupled to the VGA and operable to convert an output signal of the VGA into a digital signal; an automatic gain control (AGC) unit coupled to the ADC and operable to determine whether an amplitude of an output signal of the ADC is within a predetermined amplitude range; wherein, if the amplitude of the output signal of the ADC is outside the predetermined amplitude range, the AGC unit is operable to modify a gain associated with the VGA such that the ADC output signal has an amplitude within the predetermined amplitude range; and a first spur mitigation unit operable to determine an estimate of a spur signal of the ADC output signal and remove the spur signal from the ADC output signal based on the estimate of the spur signal, wherein the first spur mitigation unit comprises a moving average filter operable to generate the estimate of the spur signal; wherein the AGC unit is further operable to reset the moving average filter of the first spur mitigation unit when the AGC unit modifies the gain associated with the VGA.
2. The receiver of claim 1 , wherein the first spur mitigation unit is operable to determine the estimate of the spur signal of the ADC output signal and remove the spur signal from the ADC output signal based on the estimate of the spur signal when the amplitude of the ADC output signal is within the predetermined amplitude range.
3. The receiver of claim 1 , wherein, if the amplitude of the ADC output signal is greater than the predetermined amplitude range, the AGC unit is operable to increase the gain associated with the VGA such that the ADC output signal has an amplitude within the predetermined amplitude range.
4. The receiver of claim 1 , wherein, if the amplitude of the ADC output signal is less than the predetermined amplitude range, the AGC unit is operable to decrease the gain associated with the VGA such that the ADC output signal has an amplitude within the predetermined amplitude range.
5. The receiver of claim 1 , wherein the first spur mitigation unit further comprises a first multiplier, a second multiplier, and an adder, wherein the first multiplier is operable to shift the ADC output signal from a first frequency to a second frequency, wherein the moving average filter is operable to receive an output signal of the first multiplier and generate the estimate of the spur signal of the ADC output signal, wherein the second multiplier is operable to shift the spur signal estimate to the first frequency, wherein the adder is operable to receive the ADC output signal and the spur signal estimate, wherein the adder is operable to subtract the spur signal estimate from the ADC output signal to remove the spur signal from the ADC output signal.
6. The receiver of claim 1 , wherein the AGC unit is operable to reset taps of the moving average filter each time the AGC modifies the gain associated with the VGA.
7. The receiver of claim 1 , operable to process RF signals modulated using a complementary code keying (CCK) modulation technique.
8. The receiver of claim 1 , further comprising a matched root-raised cosine (RRC) filter coupled to the ADC, wherein the matched RRC filter is operable to filter the ADC output signal and provide the ADC output signal to the first spur mitigation unit and a second spur mitigation unit.
9. The receiver of claim 1 , further comprising a second spur mitigation unit operable to receive the ADC output signal, wherein the second spur mitigation unit comprises: a growing box filter operable to determine a current estimate of a spur signal of the ADC output signal, and a power measurement unit operable to determine a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal, wherein the power measurement unit is further operable to determine whether the power of the previous estimate of the spur signal is greater than the power of the current estimate of the spur signal; wherein, if the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the second spur mitigation unit is operable to remove the spur signal from the ADC output signal received at the second spur mitigation unit based on the previous spur signal estimate.
10. The receiver of claim 9 , wherein, if the power of the previous spur signal estimate is less than the power of the current spur signal estimate, the power measurement unit is operable to increase the size of the growing box filter, wherein, after increasing the size of the growing box filter, the growing box filter is operable to determine a new estimate of the spur signal of the ADC output signal.
11. The receiver of claim 9 , wherein the first spur mitigation unit is coupled to packet detection circuitry of the receiver and the second spur mitigation unit is coupled to data processing circuitry of the receiver.
12. The receiver of claim 9 , further comprising a second power measurement unit and a digital scalar unit coupled to the second spur mitigation unit, wherein the second power measurement unit is operable to determine a power of an output signal of the second spur mitigation unit, wherein the second power measurement unit is further operable to determine a scaling factor based, at least in part, on the power of the output signal of the second spur mitigation unit, wherein the digital scalar unit is operable to scale the output signal of the second spur mitigation unit using the scaling factor provided by the second power measurement unit.
13. The receiver of claim 9 , wherein the second spur mitigation unit further comprises a first multiplier, a second multiplier, and an adder, wherein the first multiplier is operable to shift the ADC output signal from a first frequency to a second frequency, wherein the growing box filter is operable to receive an output signal of the first multiplier and determine the current estimate of the spur signal of the ADC output signal, wherein, if the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the growing box filter is operable to provide the previous spur signal estimate to the second multiplier, wherein the second multiplier is operable to shift the previous spur signal estimate to the first frequency, wherein the adder is operable to receive the ADC output signal and the previous spur signal estimate, wherein the adder is operable to subtract the previous spur signal estimate from the ADC output signal to remove the spur signal from the ADC output signal.
14. A receiver for a wireless communication device, the receiver comprising: an analog-to-digital converter (ADC) operable to convert an RF signal received at the receiver to a digital signal; a spur mitigation unit operable to receive an output signal of the ADC, wherein the spur mitigation unit comprises: a growing box filter operable to determine a current estimate of a spur signal of the ADC output signal, and a power measurement unit operable to determine a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal, wherein the power measurement unit is further operable to determine whether the power of the previous estimate of the spur signal is greater than the power of the current estimate of the spur signal; wherein, if the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the spur mitigation unit is operable to remove the spur signal from the ADC output signal based on the previous spur signal estimate; and a second power measurement unit and a digital scalar unit coupled with the spur mitigation unit, wherein the second power measurement unit is operable to determine a power of an output signal of the spur mitigation unit, wherein the second power measurement unit is further operable to determine a scaling factor based, at least in part, on the power of the output signal of the spur mitigation unit, wherein the digital scalar unit is operable to scale the output signal of the spur mitigation unit using the scaling factor provided by the second power measurement unit.
15. The receiver of claim 14 , wherein, if the power of the previous spur estimate is less than the power of the current spur estimate, the power measurement unit is operable to increase a size of the growing box filter, wherein, after increasing the size of the growing box filter, the growing box filter is operable to determine a new estimate of the spur signal of the ADC output signal.
16. A method for implementing spur mitigation in a receiver of a wireless communication device, the method comprising: converting an RF signal received at the receiver of the wireless communication device into a digital signal using an analog-to-digital converter (ADC); providing an output signal of the ADC to a first spur mitigation unit in a packet detection circuit of the receiver and to a second spur mitigation unit in a data processing circuit of the receiver; at the first spur mitigation unit determining an estimate of a spur signal of the ADC output signal using a moving average filter, and removing the spur signal from the ADC output signal based on the estimate of the spur signal; at the second spur mitigation unit determining a current estimate of a spur signal of the ADC output signal using a growing box filter, determining a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal using a power measurement unit, and if the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, removing the spur signal from the ADC output signal based on the previous spur signal estimate.
17. The method of claim 16 , wherein, if the power of the previous spur estimate is less than the power of the current spur estimate, increasing a size of the growing box filter, and after increasing the size of the growing box filter, determining a new estimate of the spur signal of the ADC output signal.
18. The method of claim 16 , further comprising: determining whether an amplitude of the output signal of the ADC is within a predetermined amplitude range; if the amplitude of the output signal of the ADC is outside the predetermined amplitude range, modifying a gain associated with a VGA of the receiver such that the ADC output signal has an amplitude within the predetermined amplitude rage.
19. The method of claim 18 , further comprising, if the amplitude of the ADC output signal is within the predetermined amplitude range, determining an estimate of the spur signal of the ADC output signal and removing the spur signal from the ADC output signal based on the estimate of the spur signal using the first spur mitigation unit.
20. The method of claim 18 , further comprising resetting the moving average filter of the first spur mitigation unit when the gain associated with the VGA of the receiver is modified.
21. The method of claim 18 , further comprising, if the amplitude of the ADC output signal is greater than the predetermined amplitude range, increasing the gain associated with the VGA of the receiver such that the ADC output signal has an amplitude within the predetermined amplitude range, and if the amplitude of the ADC output signal is less than the predetermined amplitude range, decreasing the gain associated with the VGA of the receiver such that the ADC output signal has an amplitude within the predetermined amplitude range.
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December 16, 2008
March 27, 2012
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